Enterprises may sometimes wish to contact their customers to verify that a particular customer's transactions were actually performed by the customer and not by an imposter. These entities may attempt to reach out to the customer with a telephone call or an SMS text message regarding these transactions. Imposters, however, may tamper with the customer's telephone, frustrating the verification process. For instance, imposters may port the customer's telephone number, set up call forwarding on the customer's telephone account, switch the telephone hardware associated with the customer's telephone account, or set up simultaneous ring service on the customer's telephone account to intercept the call intended for the customer.